1. Field of the Disclosure
This disclosure relates generally to apparatus for use in wellbore operations utilizing progressive cavity power devices.
2. Background of the Art
To obtain hydrocarbons (oil and gas), boreholes or wellbores are drilled by rotating a drill bit attached to a drill string end. A large number of the current drilling activity involves drilling deviated and horizontal boreholes for hydrocarbon production. Current drilling systems utilized for drilling such wellbores generally employ a drill string having a drill bit at its bottom that is rotated by a motor (commonly referred to as a “mud motor” or “drilling motor”). A typical mud motor includes a power section that includes a rotor having an outer lobed surface disposed inside a stator having a compatible inner lobed-surface. Such a power section forms progressive cavities between the rotor and stator lobed surfaces. Such motors are commonly referred to as progressive cavity motors or Moineau motors. Also, certain pumps used in the oil industry utilize progressive cavity power sections.
The stator typically includes a metal housing lined inside with a helically contoured or lobed elastomeric material. The volumetric efficiency of a mud motor, to a large extent, depends upon the seal created between the lobes of the rotor and the stator during rotation of the rotor inside the stator, which efficiency depends upon the fitting between the rotor and stator lobes. Rotor lobes being on the outside, their dimensions can be precisely measured using a variety of inspection tools. Stator lobe contours being on an inner surface of the stator are generally not precisely measured. Relatively small deviations of the stator contours from the desired or designed dimensions can result in a: (i) less efficient mud motor, for example due to excessive clearance between the rotor and stator lobes compared to the optimal clearance and; (ii) reduce operating life of the motor because of excessive contact (tighter tolerances) between the rotor and stator lobes. Available devices for nondestructive measurements of the Inner contour of a device are two-point-measuring devices that measure the Inner diameter of the stator, but not the complete cross-section of the inner contour of the stator.
The disclosure herein provides apparatus and methods for measuring inner contoured profiles of devices, such as stators of mud motors, progressive cavity pumps, and tubular members.